<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script>
			var a = null;
			switch (a) {
				case 1:
					alert("number");
					break;

				case "abc":
					alert("string");
					break;

				case null:
					alert("null");
					break;

				case undefined:
					alert("undefined");
					break;

				case true:
					alert("boolean");
					break;
			}
		</script>
	</body>
</html>
